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Wednesday, September 29, 2010

Cancer Risk from CT Scan Exposure May Be Higher than You Think

According to two recent studies the cancer risk from radiation exposure may be higher than once thought. Berrington de Gonzalez and colleagues published two papers in the December 14/28, 2009 issue of Archives of Internal Medicine. One study postulates that CT scans in the U.S. in the year 2007 will lead to some 29,000 new cancers in the future. The largest number of cancers will result from CT scans of the abdomen.

The second paper investigated the variation in CT scan technique at four hospitals in the San Francisco area. The authors found wide variations in radiation dose due to different settings on the devices and the radiation exposure was much higher than previously published data suggested. For example, the median exposure from an abdominal CT scan was 31 millisieverts, a figure about four times higher than the usually quoted range.

For comparison, a CT scan of the abdomen and pelvis with contrast has an estimated radiation exposure to the patient of some 234 routine chest x-rays. A CT coronary angiogram exposes a patient to the same dose of radiation as 309 chest x-rays.

Editorialists in both Archives of Internal Medicine and JAMA expressed great concern and call for tighter regulation. The radiologists are also considering measures to try to decrease the number of CT scans done in the U.S.